The current research is investigating the effects of renal perfusion pressure on RBF, GFR and excretion. We have demonstrated that autoregulation of RBF and GFR can be dissociated from one another. In addition, through the measurement of renal oxygen consumption, we have shown that the changes in sodium excretion are passive (not involving active transport). The results of these experiments indicate that the location of the autoregulatory mechanism need not be postulated to be in the afferent arteriole.